A system for automatically guiding vehicles is known from French Pat. No. 1,131,357, the wheels of the vehicles being provided with pneumatic tyres, comprising control means which act on each of the steering levers of the wheels, and also comprising means for raising the above-mentioned control means and disengaging them from a rail, in view of guiding the vehicle in a manner other than by the rail.
This known system has the disadvantage of being unidirectional, i.e., it cannot be used in the two directions of movement.
It also has the disadvantage of not being able to prevent an excessive drift of wheels having pneumatic tires, nor being able to prevent said wheels from slipping. The safety is reduced because the system does not comprise any means for making the vehicle exactly follow the provided trajectory.
A bi-directional automatic guiding system for rigid or articulated vehicles is also known from French Pat. No. 1,131,358, the system being provided with at least one steering axle supporting wheels with pneumatic tires, possibly driving wheels, comprising at least one first roller which is to follow a rail extending in the longitudinal axis of the movement path of the vehicle, or parallel to this axis. Each roller is mounted on an arm comprising two rods each being hinged on the side of a small vertical shaft which transmits the steering pulse to a steering lever of the guide wheels of the vehicle.
This known guidance system does not allow any transverse digression of the axle and wheels with respect to the provided trajectory. Any drift, even a normal drift of wheels with pneumatic tires subjects the two rollers and the rail to transverse stresses when the rollers are attached together rigidly by the pairs of rods.
Consequently, the wheels with pneumatic tires only have a supporting function and not a transverse positioning function.
The effect of a parallelogram-shaped assembly of the arms supporting the guiding rollers is to maintain the rotational axes of the rollers parallel to the axis of the axle body. Also, while being inscribed in the curves, the rollers form with the rail an angle of incidence which brings them to revolve under unfavorable wear and noise conditions. If the curve is very pronounced, the angle of incidence may become excessive and may considerably increase the risks of derailment.
This known system does not comprise any means for lifting the guiding device which would allow the use of bimodal type vehicles, i.e., the use of vehicles which are guided alternately, either by a mechanical type of automatic device used on its appropriate infrastructure, or by the driver in an autonomous use.